Sensibly equivalent¶ to:
The N78 is a 1953 audio output pentode with a high mutual conductance, suggesting that full output can be obtained with a low input signal. In use this B7G audio output valve ran very hot.
In class AB1 push pull a pair of valves can deliver 9 Watts at 4.5% distortion. If connected as triodes the pair can deliver 6.3 Watts at 1.6% distortion.
M-OV produced these valves and branded them with paper labels: GEC for professional sales and commercially, Emitron, Marconi and Osram.
The GEC label.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 60 mm tall.
References: Datasheet & 1040. Type N78 was first introduced in 1952.
Absolute Maximum Operating Conditions¶
Updated April 29, 2018. shape:thin.glass.tube construction:all.glass type:pentode age:1950.1960 base:b7g heater:6.3v pins:7 pin:1.g1 pin:2.k.g3 pin:3.h pin:4.h pin:5.a pin:6.ic pin:7.g2